1. Field of the Invention
The present invention relates to a stator for a rotary machine that is driven by an internal combustion engine for the vehicle, for example, and a method for manufacturing the stator.
2. Description of the Related Art
FIG. 13 is a perspective view showing the conventional rotary machine (alternator for vehicle) as disclosed in U.S. Pat. No. 3,078,288, for example. In FIG. 13, a rotor 7 of landau type is rotatably attached via a shaft 6 within a case 3 composed of a front bracket 1 and a rear bracket 2, and a stator 8 is supported on an inner wall face of the case 3 to cover the outer circumferential side of the rotor 7. The shaft 6 is rotatably supported by the front bracket 1 and the rear bracket 2. A pulley 4 is secured at one end of this shaft 6 to allow a rotational torque of the engine to be transmitted via a belt (not shown) to the shaft 6. A slip ring 9 for supplying a current to the rotor 7 is secured to the other end of the shaft 6, and a pair of brushes 10 are accommodated within a brush holder 11 disposed within the case 3 to slide with the slip ring 9. A regulator 18 for regulating the magnitude of an AC voltage produced in the stator 8 is connected to a heat sink 17 fitted with a brush holder 11. A rectifier 12 electrically connected to the stator 8 for rectifying the alternating current produced in the stator 8 to the direct current is mounted within the case 3.
The rotor 7 comprises a rotor coil 13 for producing a magnetic flux by passing a current, and a pair of pole cores 20, 21, provided to cover the rotor coil 13, for forming the magnetic poles due to the magnetic flux produced by the rotor coil 13. One pair of pole cores 20, 21 made of iron have eight pawl-like magnetic poles 22, 23 projected around the outer circumferential edge at an equiangular pitch in a circumferential direction, and are oppositely secured to the shaft 6 to mate the pawl-like magnetic poles 22, 23. Further, the fans 5 are secured to both axial ends of the rotor 7. Also, the suction holes 1a, 2a are provided on the axial end faces of the front bracket 1 and the rear bracket 2, and the exhaust holes 1b, 2b are provided on both shoulder portions of the front bracket 1 and the rear bracket 2 around the outer circumference, opposed to the radial outside of the coil end groups 16a, 16b on the front side and the rear side of the stator coil 16.
The stator 8 comprises a stator iron core 15 composed of a cylindrical laminated iron core with a plurality of axially extending slots 15a being formed at a predetermined pitch in the circumferential direction, a polyphase stator coil 16 wound around the stator iron core 15, and an insulating paper 19, fitted with in each slot 15a, for electrically insulating between the polyphase stator coil 16 and the stator iron core 15 as shown in FIG. 14. And the polyphase stator coil group 16 has a plurality of coils, each of which is wave wound to take alternately an inner layer and an outer layer in a slot depth direction within the slot 15a for every predetermined number of slots, one element wire 30 being folded back outside the slot 15a on the end face side of the stator iron core 15. Herein, the stator iron core 15 to receive two pairs of three-phase stator coils 16, corresponding to the number of magnetic poles (16) for the rotor 7, so that 96 slots 15a are formed at equal interval. For the element wire 30, a long copper wire material having a rectangular cross section covered with an insulated material is employed, for example.
A method for manufacturing the stator 8 will be specifically described below with reference to FIGS. 15 to 21. First of all, 12 long element wires 30 are bent into the shapes of stylized bolts of lightning, (hereinafter described as the shape of a lightning bolt) on the same plane at the same time, as shown in FIG. 15. Then, they are folded over by a jig in a right angle direction, as indicated by the arrow in FIG. 16, and an element wire group 30A is fabricated as shown in FIGS. 17A and 17B. Similarly, an element wire group 30B having a transition connection and a lead wire are fabricated, as shown in FIGS. 18A and 18B. The element wire groups 30A, 30B are composed of six pairs of element wires, shifted by one slot pitch, each pair of element wires being arranged in such a way that two element wires 30 formed in this pattern are shifted by a pitch of 6 slots from each other and superposed in a straight part 30b, as shown in FIG. 21. And six end wires of the element wire 30 extend out on either side at either end of the element wire groups 30A, 30B. Also, the turn portions 30a are aligned at either side portion of the element wire groups 30A, 30B.
On the other hand, a certain number of main laminated plates 15d made of an SPCC material having a trapezoidal slot 15a and the teeth 15c formed at a predetermined pitch (an electrical angle of 30xc2x0) are laminated, and laser welded at a predetermined position on the outer circumference, thereby producing a laminated iron core 150 of roughly rectangular parallelopiped.
As shown in FIGS. 20A and 21, the insulating paper 19 is fitted into the slot 15a of an iron core 36, each straight section of two element wire groups 30A, 30B superposed being pushed into each slot 15a. Thereby, two element wire groups 30A, 30B are attached around the laminated iron core 150, as shown in FIG. 20B. At this time, the straight portion 30b of the element wire 30 is insulated from the laminated iron core 150 by the insulating paper 19, and accommodated within the slot 15a, four wires being aligned radially. Also, two element wire groups 30A, 30B are fitted in superposition around the laminated iron core 150, as shown in FIG. 21. Then, the laminated iron core 150 is rounded, the end faces 15 being brought into contact with each other and welded together, whereby the cylindrical stator 8 is produced as shown in FIG. 20C.
However, in the conventional alternator for the vehicle, since the insulation between the stator coil group 16 and the stator iron core 15 was made by the insulating paper 19, as described above, there was a problem that the material cost of the insulating paper 19 was taken, a greater number of steps were required, and the costs were increased. Also, there was a further problem that the insulation process such as coating was required as another step on a portion where the iron core portion was exposed, thereby increasing the number of steps.
At a step of forming the stator iron core 15 cylindrically, an excessive stress occurs in the teeth 15c of the stator iron core 15, and a laminated steel plate making up the teeth 15c is deformed and shifted circumferentially on the inner diameter side of the stator iron core 15, disordering a magnetic circuit, resulting in a problem of lower output voltage. And since the insulation between the stator iron core 15 and the stator coil 16 is made by the insulating paper 19, when the teeth 15c is deformed, the insulating paper 19 is ruptured, resulting in a problem of causing a short-circuit with the stator coil 16.
When the stator coil group 16 is inserted in the slot 15a of the stator iron core 15 in a direction of the arrow A, as shown in FIG. 21, or when molding the stator iron core cylindrically, as shown in FIG. 20C, a reaction force from the stator coil group 16 is exerted. In particular, the stator iron core 15 is molded cylindrically around the neutral axis on the almost central portion of the core pack, whereas each coil group 16 is deformed cylindrically around the neutral axis of each coil group 16. Therefore, the displacement of the stator iron core 15 and each coil group 16 are different, so that a greater stress is exerted on the teeth 15c. Accordingly, a contact occurs between the opening edge of the axial end face for the stator iron core 15 and the stator coil group 16, and the insulating paper and the insulation film for the stator coil group 16 are exfoliated, resulting in a problem of causing a pressure-proofing failure.
Further, the insulating paper 19 is interposed between the stator iron core 15 and the stator coil group 16, whereby there is a gap between the inner wall face of the slot 15a and the insulating paper 19. Therefore, due to an insulation failure caused by a dislocation when inserting the stator coil group 16, or the water content permeating into the gap, or a bad thermal conduction (coolness) between the stator coil group 16 that is a heat generating body and the stator iron core 15, there was a problem that the alternator for vehicle was degraded in quality.
This invention has been achieved in the light of the aforementioned problems, and it is an object of the invention to provide a stator for a rotary machine and a method for manufacturing the stator, in which the stator has a high insulation and cooling performance, and can be produced in simple manner, with high quality and lower costs.
To achieve the above object, according to this invention, there is provided a stator for a rotary machine comprising a rotor and a stator having a stator iron core disposed opposite around the outer circumference of the rotor and a stator coil fitted around the stator iron core, wherein the stator iron core has a laminated iron core with a plurality of axially extending slots formed at a predetermined pitch along a circumferential direction, an insulating resin is coated at least on an axial end face of the stator iron core and an inner wall face of a slot in the laminated iron core to provide insulation between the stator iron core and the stator coil, and the laminated iron core is formed in a cylindrical shape by bringing both circumferential end portions of the laminated iron core into contact with each other in such a way as to bend the laminated iron core so that an open face of the slot on the inner circumferential side may be directed inside.
The insulating resin is coated thicker on the axial end face of the stator iron core than on the inner wall face of the slot on the axially central portion.
The insulating resin is coated thicker near an opening face of the stator iron core on the inner circumferential side than any other portion of the inner wall face of the slot.
The insulating resin is coated to take an R shape or chamfered shape on the axial end face of the stator iron core.
The insulating resin is coated to take an R shape or chamfered shape on the axial end face of the stator iron core.
The insulating resin on the axial end face of the stator iron core is coated thicker on the inner diameter side of a core back neutral with respect to the axis than on the outer diameter side.
The insulating resin on the inner wall face of the slot is coated thinner on the outer circumferential side of the stator iron core than any other portion of the inner wall face.
A notch is provided on the inner wall face of the slot on the outer circumferential side of the stator iron core, and the insulating resin is coated thinner in the notch than any other portion of the inner wall face.
The axial end face of the stator iron core is formed in an irregular formation.
The inner wall face of the slot is formed in the irregular formation.
The insulating resin is coated thinner on both ends of the laminated iron core in the circumferential direction than any other portion of the laminated iron core.
The insulating resin is an epoxy based insulation resin, or a silicone based insulating resin.
The stator coil is inserted into the slot to be aligned in one row in a diameter direction of the stator iron core.
The stator coil has a substantially rectangular shape in cross section.
The stator coil has a plurality of coils folded back outside the slot on the end face side of the stator iron core and wound to take alternately an inner layer and an outer layer in a slot depth direction within the slot for every predetermined number of slots, and a turn portion of the coil element wire folded back outside the slot on the end face side of the stator iron core is aligned in the circumferential direction to constitute a coil end group.
According to this invention, there is provided a method for manufacturing a stator for a rotary machine including a step of forming a laminated iron core by laminating a straight steel plate sheet with a slot shape punched, a step of coating an insulating resin at least on an axial end face of a stator iron core and on an inner wall face of a slot in the laminated iron core, a step of forming the cylindrical stator iron core by placing the both circumferential ends of the laminated iron core coated with the insulating resin into contact with each other, and a step of winding a stator coil around the stator iron core.
Also, according to this invention, there is provided a method for manufacturing a stator for a rotary machine including a step of forming a laminated iron core by laminating a straight steel plate sheet with a slot shape punched, a step of coating an insulating resin at least on an axial end face of a stator iron core and on an inner wall face of a slot in the laminated iron core, a step of winding a stator coil around the laminated iron core coated with the insulating resin, and a step of forming the cylindrical stator iron core by placing both circumferential ends of the laminated iron core having the stator coil wound into contact with each other.
The insulating resin is applied by electrostatic powder coating.
The insulating resin is applied from an opening face of the slot on the inner circumferential side of the stator iron core.
The insulating resin is applied on the stator iron core in an axial direction.
The stator coil is molded beforehand in an arranged state within the slot, and then inserted into the slot.